Handbook of Solvents - George Wypych - ChemTech - Ventech!

1434 Aydin K. Sunol and Sermin G. Sunol
where:
λ thermal conductivity
η viscosity
M molecular mass
ρrm reduced molar density
ω accentric factor
p dipole moment
pr reduced dipole moment
Vcm critical molar volume
Tc,Tr critical and reduced temperature
κ polar parameter
For low pressures, f1 is reduced to 1.0 and f2 is reduced to zero. This gives the
Chung-Lee-Starling expression for thermal conductivity of low pressure gases. The molar
density, ρrm, can be calculated using and equation of state model (for example, the
Peng-Robinson-Wong-Sandler equation of state) where the mixing rule for b is obtained as
follows. The second virial coefficient must depend quadratically on the mole fraction:
BT () = ∑∑xxB
with:
B
ij
=
i
j
i j ij
( Bii + Bij
)
( 1−
kij
)
2
The relationships between the equation of state at low pressure and the virial coefficient are:
a
ai
B = b − ; Bii = bi−
RT RT
Wong and Sandler has shown that the following mixing rule does satisfy the second
virial coefficient equation:
∑∑
xxB
i j
b =
E
Am( p =∞) 1−
−
ΛRT
i j ij
∑
i
xB
i ii
where:
B the second virial coefficient
kij the interaction coefficient of the molecules i and j
b function of Tci and Pci and xi a function of Tci, Pci, xiand kij A E m Helmholtz free energy
The pressure correction to the thermal conductivity for a pure component or mixture at
low pressure is given by:
( ( ) rm i i ci ci ci )
v v
λ = fcn λ p =0, ρ , y , M , T , V , Z